Grand Master Hardin began his training over 40 years ago in December of 1968. As a red belt, he taught a club at the YMCA in Warren, Arkansas, later expanding to the YMCA in Hot Springs, Arkansas. In 1971, he opened a full time school in Hot Springs. He taught there until 1982, when he sold his Hot Springs school and moved to Nashville, Tennessee, to open a school and begin development of the Tennessee region. He also was a member of the staff of Henderson State University teaching Taekwondo there from 1975 to 1982. During this time he was very active with the American Taekwondo Association (ATA), achieving the position of ATA Regional Vice President in 1980.

In 1984, Grand Master Hardin, then a 5th Degree Black Belt, founded the Mid American Taekwondo Centers (MATC), a network of schools interested in training and competing together. He also developed the Choong Sil style of Taekwondo, which integrates a goal-oriented philosophy as part of the Taekwondo training. In the summer of 1995, the last pattern in the Choong Sil system was introduced and the Choong Sil pattern system was completed. In keeping with this, the MATC elected to change its name to the Choong Sil Taekwondo Federation (CTF). The CTF now encompasses schools and clubs, headquartered in the Ozark Mountains of Arkansas, and with schools as far away as the East and West Coasts.

Grand Master and Mrs. Hardin, herself a sixth degree black belt, spent the last few years building and developing a Lodge and new Camp Facility for the CTF in the Ozark Mountains of Arkansas. The CTF Headquarters was moved there in December 1999 from Nashville, Tennessee. This facility is designed for use as a retreat for CTF members and a permanent facility for Black Belt Training Camps throughout the year. In addition to the Lodge, the facility is located on a full working ranch with cattle, bison and even a llama. With its location in the Ozark National Forest, this is an ideal vacation spot for instructors who enjoy outdoor activities such as hunting, fishing, canoeing, hiking, camping, etc.

Over the years, the CTF has been involved with other Taekwondo organizations such as the ITF, GTF, AAU and USTL, primarily for competitive opportunities. In early 2011, the World Tae Kwon-Do organization appointed Grandmaster Hardin as its temporary Secretary General and Mrs. Hardin as Executive Director. These appointments were confirmed as permanent appointments by a meeting of the Tae Kwon-Do pioneers in Dallas, TX in July 2011. It is a great compliment to the CTF to be affiliated with the WTA in this manner and opens doors to the highest level of certification available in the world today, that of the original pioneers of Tae Kwon-Do. It is also an opportunity for the CTF to play a key role in the future development of Traditional Tae Kwon-Do throughout the world.